Fiber-reinforced resin-type composite materials that combine a fibrous material with a matrix resin are light and exhibit a high stiffness, and as a consequence moldings that use these fiber-reinforced resin-type composite materials are widely used as, for example, machine components, components in electrical•electronic devices, vehicle components and members, and device components for aerospace applications. For example, glass fibers, carbon fibers, ceramic fibers, and aramid fibers are used for the fibrous material.
On the other hand, thermosetting resins, e.g., unsaturated polyester resins, epoxy resins, and so forth, are typically used for the matrix resin based on considerations such as mechanical strength, moldability, and compatibility with fibrous materials. However, a crucial drawback to fiber-reinforced resin-type composite materials that use a thermosetting resin is that they cannot be re-melted and remolded.
So-called stamping molding materials are also known as composite materials that employ a thermoplastic resin as the matrix resin. Stampable sheet having reinforcing fiber and thermoplastic resin as its main components is used as a substitute for fabricated metal articles because it can be molded into complex shapes, has a high strength, and is light.
The use of polyethyleneterephthalate and polyamide 6 has also been disclosed for thermoplastic resin-based fiber-reinforced plastics (refer to Patent References 1 and 2), while moldings that use a polyamide resin and an epoxy resin have been disclosed as fiber-reinforced plastics that use both a thermoplastic resin and a thermosetting resin (refer, for example, to Patent Reference 3). These composite materials, however, have exhibited a deficient impact resistance, warping resistance, recycling performance, and productivity.
Molding methods that bring about an improved productivity with thermoplastic resin-based fiber-reinforced plastics have also been disclosed (refer to Patent References 4 and 5), but the strength and dimensional stability of the moldings provided by these methods have not been satisfactory.
Moreover, there is demand for additional improvements in the properties of fiber-reinforced plastics; for example, there is demand for improvements in the impact resistance, elastic modulus, resistance to warpage, dimensional stability, heat resistance, weight reduction, recycling characteristics, moldability, and productivity.
Unlike, for example, polyamide 6 and polyamide 66, xylylenediamine-based polyamide resins, which employ xylylenediamine as a diamine component, have an aromatic ring in the main chain and as a consequence exhibit a high mechanical strength, a high elastic modulus, a low moisture absorption rate, and an excellent oil resistance and when molded exhibit a low mold shrinkage rate, few shrinkage cavities, and little warping. Thus, the use of a xylylenediamine-based polyamide resin for the matrix resin can be expected to provide a novel composite material that has excellent properties.
However, xylylenediamine-based polyamide resins have a slow crystallization rate, poor stretching characteristics, and a poor moldability, and as a result it has been difficult to produce composite materials that employ a xylylenediamine-based polyamide resin and there has continued to be demand for the production of a novel, xylylenediamine-based polyamide resin/fibrous material composite material that exhibits excellent physical characteristics.